Technicians will conduct leak checks today on the quick disconnects for space shuttle Discovery's forward reaction control system and auxiliary power units. The shuttle is at Launch Pad 39A at NASA's Kennedy Space Center in Florida, the launch site of all the shuttle missions.

At NASA's Johnson Space Center in Houston, training home to the astronauts, the STS-133 crew will practice procedures in the Neutral Buoyancy Laboratory for the mission's first spacewalk.

During space shuttle Discovery's final spaceflight, the STS-133 crew members will take important spare parts to the International Space Station along with the Express Logistics Carrier-4. Discovery is being readied for flight inside Kennedy's Orbiter Processing Facility-3 while its solid rocket boosters are stacked inside the nearby Vehicle Assembly Building. STS-133 is slated to launch Nov. 1.

Space shuttle Discovery, joined to its external fuel tank and twin solid rocket boosters, is standing on its mobile launcher platform inside the Vehicle Assembly Building today as technicians get ready to move it to the launch pad this evening. A crawler-transporter has been positioned just outside the VAB's mammoth doors and will move inside later today so the stack can be placed on its sizeable back for the move. The rollout at NASA's Kennedy Space Center in Florida will take about six hours. Discovery's crew of six astronauts are to perform an integrated entry simulation today at their training base at NASA's Johnson Space Center in Houston.

The Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite acquired data for this map of ozone concentrations over Antarctica on September 12, 2010. OMI is a spectrometer that measures the amount of sunlight scattered by Earth’s atmosphere and surface, allowing scientists to assess how much ozone is present at various altitudes — particularly the stratosphere — and near the ground.

So far in 2010, the size and depth of the ozone hole has been slightly below the average for 1979 to 2009, likely because of warmer temperatures in the stratosphere over the far southern hemisphere. However, even slight changes in the meteorology of the region this month could affect the rate of depletion of ozone and how large an area the ozone hole might span. You can follow the progress of the ozone hole by visiting NASA’s Ozone Hole Watch page.

September 16 is the International Day for the Preservation of the Ozone Layer, a commemoration of the day in 1987 when nations commenced the signing of the Montreal Protocol to limit and eventually ban ozone-depleting substances such as chlorofluorocarbons (CFCs) and other chlorine and bromine-containing compounds. The ozone scientific assessment panel for the United Nations Environment Program, which monitors the effectiveness of the Montreal Protocol, is expected to release its latest review of the state of the world’s ozone layer by the end of 2010. (The last assessment was released in 2006.) Newman is one of the four co-chairs of the assessment panel.

The moon is the Earth's nearest celestial neighbor and a geologic wonderland. There are mountains that are many miles high, lava flows several hundred miles long and enormous lava tubes and craters of every size. It is the brightest object in the night sky and has profoundly influenced the course of human civilization.

For early humans, the moon provided lighting for hunting and defined when crops should be planted and harvested. Markings of lunar phases appear in cave paintings in France and defined the arrangement of Stonehenge.

The 2010 International "Observe the Moon Night" is happening on Saturday, Sept. 18. On Thursday, Sept. 16, at 3:00 p.m. EDT, Dr. Rob Suggs of NASA's Marshall Space Flight Center in Huntsville, Ala., will answer your questions about the moon and National Observe the Moon Night. Joining the chat is easy. Simply return to this page a few minutes before the chat time on Thursday. The chat module will appear at the bottom of this page. After you log in, wait for the chat module to be activated at 3:00, then ask your questions!

How does the Aqua satellite "see" sea ice? Microwaves. Everything on Earth’s surface -- including people -- emits microwave radiation, the properties of which vary with the emitter, thereby allowing the AMSR-E microwave sensor on Aqua to map the planet.

Ice emits more microwave radiation than water, making regions of the ocean with floating ice appear much brighter than the open ocean to the AMSR-E sensor. This difference allows the satellite to capture a sea ice record year-round, through cloud cover and the months of polar night. Continuous records are important because sea ice is dynamic. Besides melting and freezing, the ice moves with wind and currents which can cause it to split or pile up.

"The data from AMSR-E and other NASA satellites are critical for understanding the coupling between sea ice and the ocean and atmosphere," said Tom Wagner, Cryosphere program manager at NASA Headquarters in Washington. "It’s important for us to understand these connections to improve our predictive models of how the planet will change."

Cruising past Saturn's moon Dione this past weekend, NASA's Cassini spacecraft got its best look yet at the north polar region of this small, icy moon and returned stark raw images of the fractured, cratered surface.

The new images also show new views of the long, bright canyon ice walls, which scientists working with NASA's Voyager spacecraft called "wispy terrain" in the early 1980s. These ice walls thread along the surface of the moon's trailing hemisphere and cut across craters.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

On the sun, magnetic reconnection causes solar flares more powerful than several atomic bombs combined. In Earth's atmosphere, magnetic reconnection dispenses magnetic storms and auroras, and in laboratories on Earth it can cause big problems in fusion reactors.

Although the study of magnetic reconnection dates back to the 1950s and despite numerous scientific papers addressing this perplexing issue, scientists still cannot agree on one accepted model.

In 2014, NASA is scheduled to launch a satellite that will greatly increase our understanding of this phenomenon when it launches the Magnetospheric Multiscale (MMS) mission, a suite of four identical spacecraft that will study magnetic reconnection in the best possible laboratory – the Earth’s magnetosphere. The spacecraft will obtain measurements necessary to test prevailing theories as to how reconnection is enabled and how it progresses.